Under-carriage with three wheels arranged on the same shaft



March l1, 1969 R. I uclEN-r 3,432,124

UNDER-CARRIAGE wITH THREE wHEEEs AHRANGED oN THE SAME SHAFT Filed March .'5, 196'? United States Patent O 3,432,124 UNDER-CARRIAGE WITH THREE WHEELS ARRANGED N THE SAME SHAFT Rene Lucien, Neuilly-surSeine, France, assiguor to Societe Anonyme, Messier, Paris, France Filed Mar. 3, 1967, Ser. No. 620,421 Claims priority, application France, Mar. 7, 1966, 5 5

U.S. Cl. 244-103 7 Claims Int. Cl. B64c 25/34, 17/02 ABSTRACT 0F THE DISCLOSURE The present invention relates to an under-carriage with three wheels arranged on the same shaft.

When the conditions of strength of landing runways require an aircraft under-carriage to comprise a number of wheels greater than two, it may be advantageous to arrange three wheels on a single shaft in preference to four wheels mounted on a bogie.

This solution in fact enables the volume occupied by the under-carriage in the fuselage to be reduced on the one hand, and on the other it permits the aircraft to pivot about the under-carriage during turns on a small turning circle.

An object of the present invention is to arrange the members of the lower part of the under-carriage with three wheels on the same shaft in such manner that the removal of the central wheel can be easily and rapidly effected.

This advantageous result is obtained in accordance with the invention `by utilizing an under-carriage in which a half-fork carries a double axle constituting the common axis of rotation of the central wheel and one of the outside wheels, an arm articulated on this half-fork carrying an overhung stub-axle which constitutes the axis of rotation of the other outside wheel, the adjacent extremity of the double axle being engaged in the said stub axle, and means being provided for coupling the lower extremity of the articulated arm to the adjacent extremity of the double axle.

In order to remove the central wheel of this undercarriage, it is in consequence only necessary to free the articulated arm from the `double axle and to pivot it about the articulation which couples it `to the half-fork, in order to free a space sufficient to remove the central Wheel easily.

One form of embodiment of the invention will be described hereinafter in detail, by way of example only and not in any limitative sense, reference being made to the accompanying drawing, in which:

FIG. 1 is an axial section of the bottom portion of the under-carriage;

ICC

FIG. 2 is a detail view taken in the 'direction of the arrow F of FIG. l;

FIG. 3 is a diagrammatic illustration of a braking device of one of the wheels of the under-carriage; and

FIG. 4 is a diagrammatic illustration of another arrangement for the braking device of FIG. 3.

The lower part of the landing gear shown in FIG.l 1 comprises a half-fork 1 rigidly xed to the sliding portion of the landing gear in the case of an under-carriage with vertical travel of the shock-absorbers, or constituting the rocking lever in the case of an under-carriage having a lever and drawn wheels.

The lower extremity of the half-fork carries an axle 2, on which two wheels 3 and 4 are mounted in rotation.

The braking systems 5 and 6 of the wheels 3 and 4 are coupled to the half-fork 1.

An arm 7, articulated on the one hand at pin 8 to the half-fork 1 is coupled on the other hand to the extremity of the axle 2 by a removable shaft 9 (FIG. 2) or by any other appropriate means. At the lower extremity of the articulated arm 7 is fitted a stub-axle 10 which carries a wheel 11, and in which is engaged the adjacent extremity of the axle 2. The `braking system 12 of the wheel 11 is coupled to the articulated arm 7.

In order to remove the wheel 4 the under-carriage is lifted by a jack, and the removal of the wheel 4 is effected in the following manner:

The shaft 9 is first withdrawn in order to disengage the articulated arm 7 from the axle 2. Rotation of arm 7 about the pin 8 to the position shown in dotted lines in FIG. l provides the necessary space for the removal of the wheel 4. As shown in FIG. 3 rotary joints 13 can be provided in the hydraulic cables for the brake system 12 at the level of the pin 8 to enable the articulated arm 7 to be pivoted, without it being necessary to disconnect the brake system 12. Alternatively the hydraulic cables can be flexible as shown in FIG. 4 for the same purpose.

The invention can equally Well be applied to undercarriages with vertical shock-absorber travel and to undercarriages of the lever type. In this latter case, the operation of rotation of the pivoted arm 7 is facilitated by the fact that the pin 8 is more inclined to the vertical and that the mass to be moved (arm, pneumatic tires, wheel and brake) remain in consequence substantially in a horizontal plane.

What I claim is:

1. An under-carriage with three wheels comprising a half-fork, a double axle rotatably mounted in said halffork and constituting the common axis of rotation of the central wheel and one of the outside wheels, an articulated a'rm on said half-fork, an overhung stub-axle supported on said arm and constituting the axis of rotation of the other outside wheel, said double axle having an end portion engaged in the said stub-axle, and means for coupling said articulated arm at the lower extremity thereof to said end portion of said double axle.

2. An under-carriage as claimed in claim 1 comprising braking systems for the two wheels carried by the double axle, said braking systems being coupled to the halffork, and a braking system for the third wheel coupled to the articulated arm.

3. An under-carriage as claimed in claim 2 wherein said braking system of the said third wheel comprises flexible pipes to permit the pivotal movement of said articulated arm without dismantling the latter said braking system.

4. An under-carriage as claimed in claim 2 wherein said braking system of the third wheel comprises a rotary joint at the level of the articulation of the arm to said half-fork to permit pivotal movement of the arm without dismantling the latter said braking system.

5. An under-carriage as claimed in claim 1 comprising a pin pivotally supporting the arm carrying the stubaxle from said half-fork.

6. An under-carriage as claimed in claim 1 wherein the double axle is coupled to the adjacent extremity of the articulated arm by a removable shaft.

7. An under-carriage as claimed in claim 1 wherein said stub-axle is fitted into the articulated arm.

References Cited UNITED STATES PATENTS 2,479,893 8/ 1949 Allard. 3,124,391 `3/1964 Dishman 301-1 FOREIGN PATENTS 945,209 7/ 1956 Germany. 640,741 7/1950 Great Britain.

10 MILTON BUCHLER, Prlrzary Examiner.

P. E. SAUBERER, Assistant Examiner.

U.S. C1. X.R. 

